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Alveolata
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Kingdom Chromista
The Alveolata
Protozoan Biodiversity
A guide to the major groupsSpecies seen in lab are marked with a
Alveolata
Alveolata All alveolates have tiny sacs (alveoli) beneath
the plasma membrane All single-celled Have tubular inner membranes (cristae) in their
mitochondria (Tubies). Three major taxa with very different adaptive
strategies Dinozoa
Dinoflagellates – some photosynthetic, others not Important in nearshore oceans
Apicomplexa (Mostly) medically important parasites; non-motile
Ciliophora Ciliates – conjugation
Dinoflagellates
Phylum Dinozoa = Dinoflagellata
Dinoflagellates Often classed with algae Cell complexity
Single cells or chains of cells. How are their cells organized?
Mesokaryotes – permanently condensed chromosomes Mitotic spindle located outside of the nucleus (which
remains intact during mitosis) What pigments do they possess?
Chlorophyll a, Chlorophyll c and Peridinin. What storage product is made?
Starch and oils.
Dinoflagellates Cell wall features?
Most dinoflagellates are encased in plates of armor. Thick cellulose plates encased in vesicles beneath the
cell membrane
Some are “naked” and lack these plates Gymnodinium
2 flagella present. One trails behind One lies in groove around center of cell Cell spins slowly like a top as it swims
Ceratium
Gonyaulax: an armoured dinoflagellate. Cell wall is subdivided into multiple polygonal vesicles filled with relatively thick cellulose plates
A “naked” dinoflagellate. Cell wall does not have thickened cellulose armour plates.
Armored dinoflagellate: Know: cingulum, sulcus, epitheca, hypotheca, flagella
Dinoflagellates
Dinoflagellates Some have elaborate eyespots called ocelli, which
have a pigmented portion and a lens-like refractive portion.
Some have trichocysts, which are ejectile organelles similar to the nematocysts in Cnidarians. What other group of protists has these?
Ceratium
Ceratium
Note: nuclei with permanently condensed chromosomes
Dinoflagellates Mature dinoflagellates are haploid (1n)
Dikaryotic nuclei – 2 haploid nuclei Permanently condensed chromosomes
Reproduction Mostly asexual Reproduce by fission A few can reproduce sexually
Gametes formed by mitosis (not meiosis) because the cells are already haploid.
Gametes (1n) are motile Zygotes (2n) formed by fusion of gametes also motile
mei
osis
Dinoflagellates Ecology
90% are marine 10% freshwater About 50% are photosynthetic; the rest are heterotrophs
(parasites) Photosynthetic dinoflagellates are second only to
diatoms as primary producers in coastal waters. May be free-living or symbiotic
Zooxanthellae - symbionts of cnidarians and others Vital to the growth and survival of coral reefs
Zooxanthellae Dinoflagellate endosymbionts of animals and
protozoa Coral reef builders
Zooxanthellae Symbiotic dinoflagellates found in many marine
invertebrates Genus Symbiodinium Sponges, corals, jellyfish, Tridacnid clams and flatworms Also found within protists, such as ciliates, foraminiferans,
and colonial radiolarians.
Zooxanthellae
Zooxanthellae Endosymbionts of animals and protozoa In coral polyps zooxanthellae are found in the
second layer of cells below the epidermis; one algal cell per animal cell.
Important components of reef building corals* Provide them with nutrients Remove waste Contribute to the production of calcium carbonate
skeletons
* More about this when we study Cnidarians
Zooxanthellae Mutualism
Host organism ingests the dinoflagellate and incorporate it into its own tissues without harming it.
Dinoflagellate divides repeatedly, and begins to manufacture carbohydrates which are provided to the host.
Many corals get all their food from the zooxanthellae; build reefs much faster with the dinoflagellates present in their tissues.
Zooxanthellae
Zooxanthellae Recall observations on zooxanthellae in tissues of Aiptasia anemones from S219 aquarium
Cassiopeia jellyfish (aquarium) also have zooxanthellae and typically rest upside down in shallow mangrove beds. This provides maximum sun exposure for symbionts Jellyfish also feeds on passing zooplankton Blue structures are vesicular appendages that hold
zooxanthellae
Aiptasia anemone with zooxanthellae
The upper layer of the Acropora sp. is the epidermis. The lower layer is the gastrodermis. Within the cells are round to oval golden spheres. These are the zooxanthellae.
Cassiopeia, the Upside-Down Jelly or Mangrove Jelly (Figure 7), generally lies on upside-down on the substrate where it tends its internal garden of zooxanthellae, which give it a greenish color. While there, the bell margins pulsate creating a current across the oral surface where plankton and other particles are subdued by nematocysts and caught in a gelatinous coating. The captured particles are carried to the mouth or to other secondary mouths that occur on the oral arms. These are animals of warm, shallow water of the West Indies, the Pacific, and the Indian Oceans.
Coral Bleaching = loss of zooxanthellaeCauses – discussed with Cnidarians
Bioluminescent Dinoflagellates
Bioluminescence
Some dinoflagellates are capable of producing light - bioluminescence Molecules made by the organism produce light in
a chemical reaction. Luciferin and luciferase
Same reaction that occurs in fireflies
Health Issues Many dinoflagellates produce neurotoxins
Poisons that injure the nerves of marine life that feed on the dinoflagellates
May cause massive kills of fish and shellfish, as well as other forms of marine life.
If animals containing these toxins are eaten by humans, the result may be illness or even death. Neurotoxins affect muscle function, preventing
normal transmission of electrochemical messages from the nerves to the muscles by interfering with the movement of sodium ions through the cellular membranes
Health Issues These toxins in the water can blow inland in sea
spray and cause temporary health problems for people who live near the coast.
The toxin from Gonyaulax catenella is so toxic that an aspirin sized tablet of the poison could kill 35 people; it is one of the strongest known poisons
Neurotoxins Saxitoxin - most common dinoflagellate toxin
100,000 times more potent than cocaine Found in North American shellfish from Alaska to
Mexico, and from Newfoundland to Florida Brevitoxin
Causes fish kills May also cause poisoning in humans when it accumulates
in the tissues of shellfish Red Tides
Population explosions of dinoflagellates that can color the water red.
Shellfish contain high levels of toxins during these times
Gonyaulax and views of red tidesA red tide results from a population explosion of dinoflagellates (an algal bloom). Cell densities are so high that they turn the water a red color.
Boat
Bioluminescent Red Tide
Noctiluca
Noctiluca - a bioluminescent marine dinoflagellate; also causes red tides. Can feed heterotrophically by using its longer posterior flagellum to capture prey.
Neurotoxins Humans may be poisoned:
By eating contaminated fish - Ciguatera Or by eating shellfish, such as clams or mussels -
paralytic shellfish poisoning or PSP. Poisoning is serious but not usually fatal.
Lethal concentrations lead to death from respiratory failure and cardiac arrest within twelve hours of consumption
Old rule of thumb was that shellfish should only be eaten during months with an "R" in them, and not during May to August. Summer brings runoff of nutrients and blooms of dinoflagellates. NOT VERY RELIABLE!
Pfiesteria piscicida Ulcers on fish caused (?) by PfiesteriaNote the long flagella
Pfiesteria and some of its relatives cause death in fish and respiratory and neurological complications in humans
Ciliates
Phylum Ciliophora
Functional groupings of ciliates Holotrich- uniform ciliation Heterotrich- possess membranes &/or cirri Peritrich- cilia only around the cytostome Colonial-living in colonies Suctorian- a clade of Ciliophora possessing
hollow feeding tentacles
An assortment of freshwater ciliates- biodiversity!
This figure shows 167 species- about 9500 species are known
Ciliophora (ciliates)
A major clade within the Alveolates. Synapomorphies* of ciliates include:
Ciliated pellicle and associated kinetodesmata Dimorphic nuclei Conjugation
Primarily holotrophic - few parasitic. Many can form cyst stage (resting stage).
*Shared, derived characteristic – something NEW!
c
Stentor coeruleus
Vorticella
Cirriciliary organelles used for food handling and locomotion- form membranes or bundles
Ciliophora
Euplotesa heterotrich ciliate showing complex cirri used for feeding and locomotion
Spirostomum
Didinium
http://www.uga.edu/protozoa/portal/images/movies/didinium.mov
Acineta
AcinetaSphaerophrya
Acineta
Balantidiasis – Balantidium coli Most cases are asymptomatic.
Clinical manifestations, when present, include persistent diarrhea, occasionally dysentery, abdominal pain, and weight loss.
Symptoms can be severe in debilitated persons.
Diagnosis is based on detection of trophozoites in stool specimens or in tissue collected during endoscopy. Repeated stool samples necessary to find trophozoites
Treatment: Tetracycline with metronidazole and iodoquinol as alternatives
Trophozoites
Cyst
B. coli trophozoites
Ichthiopthirius multifilis (Ich)
Common parasite of freshwater and marine fishes
Trophozoite burrows in skin
Mature trophozoite leaves fish and encysts.
Multiple mitoses produce hundreds of “swarmers” that reinfest fish.
Ich trophozoite in fin of freshwater drum
M. C. Barnhart
